Update to 1.5021

Upstream changes:
1.5021 Thu Jan 31 00:42:28 PST 2013
  [Improvements]
      - Added new --verify option that enables verifying CHECKSUM and SIGNATURE for distributions
        from CPAN/PAUSE

1.5020 Tue Jan 29 10:29:08 PST 2013
  [Bug Fixes]
      - Fixed a bug in --cascade-search that was checking a wrong version from 02packages file (Bryce Baril)
      - Added a workaround for older version of File::Temp bug (kentnl)

(wen)